HIGH FLYERS THINK TANK
Biotechnology and the future of Australian agriculture
The Shine Dome, Canberra, 26 July 2005
Case studies
Biotechnology and the Australian banana industry: A successful partnership!
Drought-resistant wheat and model species for crop biotechnology
The development of yabby aquaculture in Australia
Biotechnology and the Australian banana industry: A successful partnership!
by Dr Sharon Hamill
The $300 million Australian banana industry has benefited from biotechnology tools since the early 1980s. Biotechnology for Australian banana growers means a multi-pronged approach, using plant tissue culture for domestic and international biosecurity and for crop improvement together with an increasing arsenal of molecular diagnostic tools.
The commercial banana industry relies on monoculture of the Cavendish cultivar 'Williams' (AAA) and to a lesser extent the non-Cavendish cultivar 'Lady Finger' (AAB). There is now also increasing production of niche market varieties.
Banana growers in Australia have employed various strategies against serious plant pathogens since the 1900s when the fledgling industry in New South Wales and southeast Queensland was almost decimated by Banana Bunchy Top Virus, a virus spread host to host by aphid. Since then other viruses, such as Banana Streak Virus, have been identified.
Australian scientists have been developing diagnostic tests for a suite of viruses since the 1980s. In the 1930s Race 1 of Fusarium wilt decimated global plantations reliant on the susceptible Gros Michel variety. Australian growers of the resistant Cavendish were not badly affected; however, since 1976, a new Race 4 of subtropical Fusarium wilt has been attacking this previously resistant variety and in 1997 a more virulent Tropical Race 4 was identified in the Northern Territory.
The use of strict domestic quarantine has contained areas of Fusarium wilt, which is spread in soil, water and in affected planting material used to propagate this sterile crop. Australian scientists have undertaken significant research in Fusarium oxysporum f. sp. cubense and developed the molecular methods to determine genetic diversity and facilitate pathogen identification.
There is a need for clean planting material to ensure crops can be established and grown without risk of introducing pathogens, including virus, and to gain access to new varieties. Varieties resistant to the devastating pathogens are needed to control and manage established and ever threatening exotic pathogens.
Australian banana biotechnology research has been leading the world since the 1980s. Australian research has resulted in global improvements to quarantine and a tightening of international policy to reduce transmission of pathogens.
In 1994, Queensland Department of Primary Industries and Fisheries scientists established the world’s best banana clean planting scheme based on virus indexed tissue culture. Scientists also maintain a banana tissue culture quarantine import laboratory and one of only three globally recognised banana virus indexing centres to support the clean plant scheme and to safely import new varieties. Australia now has one of the largest and best managed banana germplasm collections maintained in vitro to facilitate research and industry development.
The availability of new varieties as clean planting material has contributed directly to a growing market of niche banana varieties. Varieties from this collection are also used to identify resistance to pathogens. Black Sigatoka resistant varieties used to replace susceptible varieties in a Northern Buffer zone have contributed to the successful program of containment and eradication of several black Sigatoka incursions that first occurred in 1983.
Black Sigatoka is an aggressive leaf pathogen causing significant crop loss. Most banana producing countries were affected by black Sigatoka via infected planting material at the same time as Australia but could not contain this serious pathogen. They now rely on often weekly fungicide application to control this pathogen that is quickly becoming resistant to many fungicides. Australia is the only country that has been able to eradicate black Sigatoka!
Success is due to disease prevention strategies, strict quarantine, clean planting material and the foresight to develop in advance the molecular diagnostic tools needed for rapid identification of black Sigatoka affected plants. Application of biotechnology has been able to directly save industry millions of dollars from potential losses from pests and diseases and provides improved production, management and sustainable practices.
Unlike the majority of commercial banana growing countries, Australia does not require heavy fungicide application against black Sigatoka, has contained devastating Banana Bunchy Top Virus and does not have Race 4 of Fusarium wilt in its major north Queensland production zone. New production areas are now established with virus indexed tissue cultured plantlets free from pests and diseases.
Biotechnology ensures that no pests or diseases are imported into Australia via new varieties and as a result Australia does not have many of the major pests and pathogens found in our neighbouring countries. Use of biotechnology continues to very successfully sustain the Australian bananna industry and protect our people and environment.
Further reading
Geering, A.D.W., Olszewski, N.E., Dahal, G., Thomas, J.E. and Lockhart, B.E.L. (2001) Analysis of the distribution and structure of integrated Banana Streak Virus DNA in a range of Musa cultivars. Molecular Plant Pathology 2, 207-213.
Hamill, S. (2003) Biotechnology delivers benefit. Australian Bananas, vol. 17, December 2003, p. 16.
Hayden, H.L., Carlier, J., and Aitken, E.A.B. (2003) Genetic structure of Mycosphaerella fijiensis populations from Australia, Papua New Guinea and the Pacific Islands. Plant Pathology, vol. 52, no. 6, pp. 703-712.
Pegg, K.G., Moore, N.Y. and Bentley, S. (1996) Fusarium wilt (Panama disease) of banana in Australia – a review. Australian Journal of Agricultural Research 47:637-650.
Smith, M.K, Hamill, S.D., Becker, D. and Dale, J. (2005) Banana and plantain. In Biotechnology of Fruit and Nut Crops, (ed. R.E. Litz), pp. 366-392. Biotechnology in Agriculture series; 29 (CAB International: Wallingford, Oxon. UK).
Thomas, J.E., Smith, M.K., Kessling, A.F. and Hamill, S.D. (1995) Inconsistent transmission of Banana Bunchy Top Virus in micropropagated bananas and its implications for germplasm screening. Australian Journal of Agricultural Research 46:663-671.
Drought-resistant wheat and model species for crop biotechnology
by Dr Barry Pogson
The 2002-2003 drought cost Australia in the order of $10 billion and 70,000 jobs. Associated with reduced rainfall is increased sunlight irradiance and temperature – all are abiotic stresses that lead to a reduction in crop yield. Plants have an integrated network of responses to minimise damage due to abiotic stresses, such as drought and excess light. However, the reduction in crop yield due to water stress is estimated at 60 per cent globally. Thus, there is a need for biotechnology applications to optimise the yield under severe and mild droughts and shorter dry intervals.
Applying fundamental research at the Australian National University and CSIRO into water-use efficiency of plants led to the development of two new drought resistant varieties of wheat, Drysdale and Rees. This resulted in yield increases of 23 per cent across 12 sites in NSW and is predicted to add more than $100 million to the industry. This is the first of many necessary steps to optimise crops for growth in the highly variable climatic conditions of Australia and a collaborative research is underway across many institutions.
The next steps require basic and strategic biotechnological research into model plant species, such as Arabidopsis, to identify gene targets. The utility of model species is demonstrated in the filing of more than 3000 patents on Arabidopsis in the US and European Patent Office in the past 3 years.
The transfer of research and IP from model species to crops is particularly efficacious when similarities and common genes occur across different species, which is often the case for abiotic and biotic stress. Once gene targets have been identified, then the knowledge needs to be transferred to crops using ‘smart breeding’ technologies that provide ‘traditional’ breeders with current and emerging biotechnological tools to rapidly integrate the desired trait into the crop of interest. In a number of instances this may also require GM to fully realise the benefits of improved and optimised crops that benefit the farmer, environment and the consumer.
The clearest example of this is Golden Rice, a high proVitamin A line developed to improve the nutritional value of rice and thereby help reduce the 100 million children who are vitamin A-deficient, of which 250,000 to 500,000 become blind every year and half die within 12 months after losing their sight. No naturally occurring rice varieties have substantial proVitamin A (carotenoids such as beta-carotene) in the grain. Thus, GM can provide a sound route to contribute to the solution of a problem of global significance.
The development of yabby aquaculture in Australia
by Professor Rocky de Nys
The development of yabby aquaculture in Australia is an excellent example of the application of biotechnology techniques to improve yield and short time to harvest. The improvement of yabby aquaculture is based on the utilisation of natural genetic diversity to provide improved breeding and selection for faster growth. The taxonomy and phylogeny of the yabby Cherax destructor complex has been elucidated using DNA sequences from the 16S rRNA gene region (Austin et al. 2003, Nguyen et al. 2004).
The determination of distinct genetic populations coupled with growth studies has subsequently facilitated the development of a selective breeding program for improved growth. Growth trials of five selected genetically distinct stocks of Cherax destructor identified significant differences in mean weight at age, with variation of 42 per cent among populations. The fastest growing population was nearly twice that of the slowest at the conclusion of the trials (Jerry et al. 2002). The identification of genetic differences in growth was then used to select founder stocks for a selective breeding program (Jerry et al. 2005).
Using within-family selection coupled with a circular mating strategy to select for faster growth rates, males and females from the selected families were 29.5 per cent and 32.7 per cent heavier than controls after two generations. This represents an average genetic gain in weight at age of 15.5 per cent. These stocks have been made available to industry to 'jump-start' the embryonic yabby aquaculture industry (CSIRO reference).
Jerry D.R., Purvis I.W., Piper L.R., Dennis C.A. (2005) Selection for faster growth in the freshwater crayfish Cherax destructor. Aquaculture 247, 169-176.
Jerry D.R., Purvis I.W., Piper L.R. (2002) Genetic differences in the growth among wild populations of the yabby Cherax destructor. Aquaculture Research 33, 917-923.
Austin C.M., Nguyen T.T.T., Meewan M.M., Jerry D.R. (2003) The taxonomy and phylogeny of the Cherax destructor complex (Decapoda : Parastacidae) examined using mitochondrial 16S sequences. Australian Journal of Zoology 51, 99-110.
Nguyen T.T.T., Austin C.M., Meewan M.M., Schultz M.B., Jerry D.R. (2004) Phylogeography of the freshwater crayfish Cherax destructor Clark (Parastacidae) in inland Australia: historical fragmentation and recent range expansion. Biological Journal of the Linnean Society 83, 539-550.
